Generally, in rig applications, such as drilling rigs and production platforms, an electric power is supplied by one or more generators. The rig applications may include pumps, motors, drive system(s), pipe racking systems, hydraulic power units, and/or a variety of rig utilities. The generators may run on natural gas or diesel fuel or other hydrocarbon fuel. In some cases, a response to external loads by an engine of these rig applications may be sluggish, when the engine runs on natural gas. Various turbochargers may be configured to utilize exhaust from the engine and supply a compressed air for operation of the engine. However, there may be a lag from turbochargers in responding to different power demands thereby effecting response of the engine to power demands. Such a sluggish response from the engines can negatively affect operations.
In order to improve the response, the engines may have to run on full load condition. In rig applications, operations are intermittent and it is difficult and/or expensive to maintain the engines at a constant heavy loading. In some situations, to compensate for sluggish engine response, artificial loads are used to keep engine loads high so that when real demands come in, the real power demand will take the portion released by the reduction of the artificial loads. However, it is not cost effective to provide full load all the time, as engines burn fuel to generate power.
Furthermore, multiple turbochargers in series are widely used in diesel or natural gas engines to provide high power. The turbochargers in series can provide enough airflow for the full load operating conditions but tend to lack air flow for part load conditions.
In some situations, with multiple engines and associated turbochargers, a rig control system may operate one engine at a full load, and may slightly reduce a power output for rest of the engines. However, these engines still may have to run at relatively high load conditions to minimize the turbocharger lag. It is most cost effective to put some engines on idle condition when power demand is low. However, the response needs to be improved when the demand is coming.
For reference, U.K. Patent GB2,488,378B (hereinafter the '378 reference) is related to a vehicle powered by a turbocharged internal combustion engine. The engine has at least one air or gas nozzle positioned within an air intake duct upstream of the turbo-blower of the turbocharger and connected to receive compressed air or compressed gases from a compressed air or gas supply, such as a storage tank, on board the vehicle. The air or gas nozzle is directed to deliver at least one jet of the compressed air or gases towards the impeller of the compressor such that the expanding momentum flux of the jet or jets fills the frontal entry area of the impeller thereby entraining and accelerating the intake air arriving at the impeller and increasing the exit boost pressure produced by the turbo-blower of the turbocharger.
However, the '378 reference does not disclose a system for operation of multiple turbochargers connected in series. Therefore, there exists a need for an efficient control during a transient load change of the engine.